1. Leibniz Institute for Science Education (IPN), University of Kiel, D 24098 Kiel, Germany
2. Institute for Pure and Applied Chemistry, University of Oldenburg, D 26111 Oldenburg, Germany
3. Department of Chemistry, Didactics of Chemistry Program, University of Dortmund, D 44221 Dortmund, Germany
4. Center for Education Research and Teacher Development, University of Wuppertal, D42119 Wuppertal, Germany